1. Field of the Invention
The present invention relates to a method of making elements with profiled cross-section from sheet metal and more particularly to plate elements suitable for use as transverse elements for transmitting power in a driving belt on which the elements are arranged in a series next to and against each other running between cone pulleys.
2. Description of the Prior Art
In the prior art elements for transmitting a driving belt have been used. Such elements must meet the demand that the cross-section thereof be uniform on the whole length of the element, that the dimensions come up to the prescribed values with a very small limit and that the surface has good contact properties and a close structure. Very high demands are made to the uniformity of the surface profile so as to ensure that a driving belt composed of similar elements shows a high efficiency and a noiseless running.
Efforts have been made to produce the plates by shaping a metal strip in such a way that the cross-section has continuously the desired profile of plates to be punched thereout afterwards but said efforts have not led to acceptable results, more particularly not since, when drawing the profile ate reasonable production speed, irregularities arise and a satisfactorily planned parallelism of the bent surface cannot be obtained.
German Offenlegungsschrift No. 2,533,280, entitled "Hinge profile and method and apparatus for the manufacture of hinge plates, issued on Feb. 2, 1977 to Ed. Scharwachter, teaches a method of making profiled objects, according to which on both sides of a center line two symmetric elements are rolled and separated from each other along the center line. The difficulty with this method is that it is used for the manufacture of hinge plates with respect to which no high demands are made concerning the exactness and quality of the surface.
The insight to manufacture elements for driving belts, which elements have to meet very specific demands, is not to be derived from this publication and neither the punching at accurately preset distances with respect to the connection between the profiles.
U.S. Pat. No. 3,949,621, issued to Bernard Joseph Beusink et al (deceased) on Apr. 13, 1976, entitled "Endless belt with trapezoidal section constituted by supporting members" teaches an uninterrupted row of thin metal plates transversely mounted on a metallic pull band over the entire length thereof. The plates are pressed against each other by tensile stress in the pull band. The alignment of each plate in a plane perpendicular to the longitudinal direction of the band is maintained by coupling means between all contiguous plates preventing lateral shifting of each plate with respect to its adjointing plates but allowing a slight mutual tipping of the plates around an axis perpendicular to the longitudinal direction of the pull band and parallel to the plane thereof. The difficulty with these plates or elements is that their manufacture requires an expensive after treatment after the punching, shaping the desired profile and obtaining the desired dimensions.